APPARATUS AND METHOD FOR MULTl-LINK COMMUNICATIONS

ABSTRACT

Embodiments of an apparatus and method are disclosed. In an embodiment, a method of multi-link communications involves at an access point (AP) multi-link device, allocating Association IDs (AIDs) to non-AP multi-link devices, including allocating one of the AIDs to each of the non-AP multi-link devices, and at the AP multi-link device, generating a first indication element for the AIDs to indicate a buffered data configuration at the AP multi-link device for the non-AP multi-link devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is entitled to the benefit of U.S. Provisional PatentApplication Ser. No. 62/933,859, filed on Nov. 11, 2019, U.S.Provisional Patent Application Ser. No. 62/957,154, filed on Jan. 4,2020, and U.S. Provisional Patent Application Ser. No. 62/980,176, filedon Feb. 22, 2020, which are incorporated herein by reference.

BACKGROUND

In multi-link communications, an access point (AP) multi-link device(MLD), e.g., an AP multi-link logical device or an AP multi-link logicalentity (MLLE), can buffer data and transmit buffered data to a non-APmulti-link device through one or more communications links. For example,a wireless AP multi-link device may wirelessly transmit buffered data toone or more wireless stations in a non-AP multi-link device through oneor more wireless communications links. To facilitate the propertransmission of buffered data between an AP multi-link device and acorresponding non-AP multi-link device, communications signalinginformation (e.g., information related to buffered data and/orcommunications links) needs to be exchanged between the AP multi-linkdevice and the corresponding non-AP multi-link device. However, typicalmulti-link communications technology may not be able to efficientlyconvey communications signaling information within a multi-linkcommunications system. Therefore, there is a need for multi-linkcommunications technology that can efficiently convey communicationssignaling information within a multi-link communications system.

SUMMARY

Embodiments of an apparatus and method are disclosed. In an embodiment,a method of multi-link communications involves at an access point (AP)multi-link device, allocating Association IDs (AIDs) to non-APmulti-link devices, including allocating one of the AIDs to each of thenon-AP multi-link devices, and at the AP multi-link device, generating afirst indication element for the AIDs to indicate a buffered dataconfiguration at the AP multi-link device for the non-AP multi-linkdevices.

In an embodiment, a method of multi-link communications involves at anAP multi-link device, allocating AIDs to non-AP multi-link devices,comprising allocating one of the AIDs to each of the non-AP multi-linkdevices, and at the AP multi-link device, generating a first indicationelement for the AIDs to indicate a buffered data configuration at the APmulti-link device for the non-AP multi-link devices.

In an embodiment, the method includes at the AP multi-link device,generating a second indication element to indicate communications linkinformation associated with the buffered data configuration at the APmulti-link device.

In an embodiment, at the AP multi-link device, generating the secondindication element to indicate the communications link informationassociated with the buffered data configuration at the AP multi-linkdevice includes at the AP multi-link device, generating a link mappingbitmap (LMB) for each of the AIDs whose corresponding non-AP multi-linkdevice the AP multi-link device has a buffered data unit to be deliveredto, wherein the LMB indicates a set of designated communications linksthrough which the buffered data unit is to be delivered.

In an embodiment, the buffered data unit is an individually addressedbuffered data unit.

In an embodiment, the method further includes from the AP multi-linkdevice, transmitting the first indication element and the secondindication element to the non-AP multi-link devices in a broadcastframe.

In an embodiment, the broadcast frame comprises a beacon frame.

In an embodiment, at the AP multi-link device, generating the secondindication element to indicate the communications link informationassociated with the buffered data configuration at the AP multi-linkdevice comprises at the AP multi-link device, generating an LMB only foreach of the AIDs whose corresponding non-AP multi-link device the APmulti-link device has an individually addressed buffered data unit to bedelivered to, where the LMB indicates a designated set of communicationslinks through which the individually addressed buffered data unit is tobe delivered.

In an embodiment, at the AP multi-link device, generating the firstindication element for the AIDs to indicate the buffered dataconfiguration at the AP multi-link device for the non-AP multi-linkdevices comprises at the AP multi-link device, for each AID of the AIDS,setting a corresponding traffic indication map (TIM) component to aspecific value when the AP multi-link device has buffered data to bedelivered to a corresponding non-AP multi-link device to which the AIDis allocated.

In an embodiment, the corresponding TIM component comprises a TIM bit,and the specific value is 1.

In an embodiment, the buffered data configuration at the AP multi-linkdevice comprises information regarding an individually addressedbuffered data unit and a group addressed buffered data unit at the APmulti-link device, and at the AP multi-link device, generating the firstindication element for the AIDs to indicate the buffered dataconfiguration at the AP multi-link device for the non-AP multi-linkdevices comprises at the AP multi-link device, generating a trafficindication map (TIM) that includes a first section containinginformation regarding the individually addressed buffered data unit anda second section containing information regarding the group addressedbuffered data, where the first and second sections have non-overlappingAID ranges within the AIDs.

In an embodiment, the AP multi-link device and the non-AP multi-linkdevices are compatible with an Institute of Electrical and ElectronicsEngineers (IEEE) 802.11 protocol.

In an embodiment, a multi-link communications system includes an APmulti-link device configured to allocate AIDs to non-AP multi-linkdevices by allocating one of the AIDs to each of the non-AP multi-linkdevices and generate an indication element for the AIDs to indicate abuffered data configuration at the AP multi-link device for the non-APmulti-link devices, and the non-AP multi-link devices.

In an embodiment, the AP multi-link device and the non-AP multi-linkdevices are compatible with an IEEE 802.11 protocol.

In an embodiment, a method of multi-link communications involves at anAP multi-link device, mapping communications links that are affiliatedwith the AP multi-link device to traffic identifiers (TIDs) for a non-APmulti-link device, at the AP multi-link device, generating an indicationelement to indicate that the AP multi-link device has buffered data fora first TID of the TIDs for a the non-AP multi-link device, andtransmitting the indication element from the AP multi-link device to thenon-AP multi-link device.

In an embodiment, transmitting the indication element from the APmulti-link device to the non-AP multi-link device associated with thefirst TID comprises broadcasting the indication element from the APmulti-link device in a broadcasting frame.

In an embodiment, the broadcast frame comprises a beacon frame.

In an embodiment, the method further comprises receiving, by the APmulti-link device, a station operation status indication from the non-APmulti-link device, where the station operation status indicationcontains information regarding which station affiliated with the non-APmulti-link device is to be in an awake state.

In an embodiment, the method further comprises transmitting the buffereddata from the AP multi-link device to the non-AP multi-link devicethrough one of the communications links that corresponds to the firstTID when a station of the non-AP multi-link device operating on the oneof the communications links associated with the first TID is to be inthe awake state.

In an embodiment, the method further comprises at the AP multi-linkdevice, setting a corresponding traffic indication map (TIM) componentof the non-AP multi-link device to a specific value.

In an embodiment, the corresponding TIM component comprises a TIM bit,and the specific value is 1.

In an embodiment, the indication element comprises a bitmap.

In an embodiment, the method further comprises transmitting the buffereddata from the AP multi-link device to the non-AP multi-link devicethrough one of the communications links that does not correspond to thefirst TID when no station of the non-AP multi-link device operating onany of the communications links associated with the first TID is to bein an awake state.

In an embodiment, a method of multi-link communications involves at anAP multi-link device, mapping a first group of communications links to afirst TID and a second group of communications links to a second TID fortransmission of data to a non-AP multi-link device, where the firstgroup of communications links and the second group of communicationslinks are subset of communications links that are affiliated with the APmulti-link device, at the AP multi-link device, generating an indicationelement to indicate that the AP multi-link device has buffered data forthe first TID and the second TID, at the AP multi-link device, receivingan indication from the non-AP multi-link device that the non-APmulti-link device is in sleep state for all of the first group ofcommunications links, and that the non-AP multi-link device is in activestate on a third communications link, where the third communicationslink is within the second group of communications links, and from the APmulti-link device, transmitting the buffered data to the non-APmulti-link device through the third communications link.

In an embodiment, the buffered data is not transmitted through the firstgroup of links.

In an embodiment, the AP multi-link device and the non-AP multi-linkdevices are compatible with an IEEE 802.11 protocol.

Other aspects in accordance with the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrated by way of example of the principlesof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a multi-link communications system in accordance with anembodiment of the invention.

FIG. 2 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.

FIG. 3 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.

FIG. 4 depicts a TIM bitmap and a corresponding link mapping bitmap(LMB) that can be used in a multi-link operation by the multi-linkcommunications system depicted in FIG. 1 .

FIG. 5 depicts an example information element format for a buffered datato link mapping (BLM) element that can be used in a multi-link operationby the multi-link communications system depicted in FIG. 1 .

FIG. 6 depicts another example information element format for a BLMelement that can be used in a multi-link operation by the multi-linkcommunications system depicted in FIG. 1 .

FIG. 7 depicts another example information element format for a BLMelement that can be used in a multi-link operation by the multi-linkcommunications system depicted in FIG. 1 .

FIG. 8 depicts another example information element format for a BLMelement that can be used in a multi-link operation by the multi-linkcommunications system depicted in FIG. 1 .

FIG. 9 depicts a TIM bitmap and a corresponding LMB that can be used ina multi-link operation by the multi-link communications system depictedin FIG. 1 .

FIG. 10 depicts a TIM bitmap and a corresponding LMB that can be used ina multi-link operation by the multi-link communications system depictedin FIG. 1 .

FIG. 11 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.

FIG. 12 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.

FIG. 13 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.

Throughout the description, similar reference numbers may be used toidentify similar elements.

DETAILED DESCRIPTION

It will be readily understood that the components of the embodiments asgenerally described herein and illustrated in the appended figures couldbe arranged and designed in a wide variety of different configurations.Thus, the following more detailed description of various embodiments, asrepresented in the figures, is not intended to limit the scope of thepresent disclosure, but is merely representative of various embodiments.While the various aspects of the embodiments are presented in drawings,the drawings are not necessarily drawn to scale unless specificallyindicated.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by this detailed description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

Reference throughout this specification to features, advantages, orsimilar language does not imply that all of the features and advantagesthat may be realized with the present invention should be or are in anysingle embodiment of the invention. Rather, language referring to thefeatures and advantages is understood to mean that a specific feature,advantage, or characteristic described in connection with an embodimentis included in at least one embodiment of the present invention. Thus,discussions of the features and advantages, and similar language,throughout this specification may, but do not necessarily, refer to thesame embodiment.

Furthermore, the described features, advantages, and characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. One skilled in the relevant art will recognize, in light ofthe description herein, that the invention can be practiced without oneor more of the specific features or advantages of a particularembodiment. In other instances, additional features and advantages maybe recognized in certain embodiments that may not be present in allembodiments of the invention.

Reference throughout this specification to “one embodiment”, “anembodiment”, or similar language means that a particular feature,structure, or characteristic described in connection with the indicatedembodiment is included in at least one embodiment of the presentinvention. Thus, the phrases “in one embodiment”, “in an embodiment”,and similar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

FIG. 1 depicts a multi-link communications system 100 in accordance withan embodiment of the invention. In the embodiment depicted in FIG. 1 ,the multi-link communications system includes at least one AP (MLD) 102,and multiple non-AP MLDs 104-1, 104-2, 104-3. The multi-linkcommunications system can be used in various applications, such asindustrial applications, medical applications, computer applications,and/or consumer or appliance applications. In some embodiments, themulti-link communications system is a wireless communications system,such as a wireless communications system compatible with an Institute ofElectrical and Electronics Engineers (IEEE) 802.11 protocol. Forexample, the multi-link communications system may be a wirelesscommunications system compatible with an IEEE 802.11be protocol. In someembodiments, the multi-link communications system includes one or moreAP MLLEs and/or one or more non-AP MLLEs. Although the depictedmulti-link communications system 100 is shown in FIG. 1 with certaincomponents and described with certain functionality herein, otherembodiments of the multi-link communications system 100 may includefewer or more components to implement the same, less, or morefunctionality. For example, in some embodiments, the multi-linkcommunications system includes multiple AP MLDs, more than three non-APMLDs, and/or less than three non-AP MLDs. In yet another example,although the multi-link communications system 100 is shown in FIG. 1 asbeing connected in a certain topology, the network topology of themulti-link communications system 100 is not limited to the topologyshown in FIG. 1 .

In the embodiment depicted in FIG. 1 , the AP MLD 102 includes multipleAPs 110-1, 110-2, 110-3. The APs 110-1, 110-2, 110-3 may be implementedin hardware (e.g., circuits), software, firmware, or a combinationthereof. The APs 110-1, 110-2, 110-3 may be fully or partiallyimplemented as an integrated circuit (IC) device. In some embodiments,the APs 110-1, 110-2, 110-3 are wireless APs compatible with at leastone WLAN communications protocol (e.g., at least one IEEE 802.11protocol). For example, the APs 110-1, 110-2, 110-3 may be wireless APscompatible with an IEEE 802.11be protocol. In some embodiments, an AP isa wireless AP that connects to a local area network (e.g., a LAN) and/orto a backbone network (e.g., the Internet) through a wired connectionand that wirelessly connects to wireless stations (STAs), for example,through one or more WLAN communications protocols, such as an IEEE802.11 protocol. In some embodiments, an AP includes at least oneantenna, at least one transceiver operably connected to the at least oneantenna, and at least one controller operably connected to thecorresponding transceiver. In some embodiments, the least onetransceiver includes a physical layer (PHY) device. The at least onecontroller operably may be configured to control the at least onetransceiver to process received packets through the at least oneantenna. In some embodiments, the at least one controller is implementedwithin a processor, such as a microcontroller, a host processor, a host,a digital signal processor (DSP), or a central processing unit (CPU),which can be integrated in a corresponding transceiver. Each of the APs110-1, 110-2, 110-3 of the AP MLD may operate in a different frequencyband. For example, the AP 110-1 may operate in 2.4 gigahertz (GHz)frequency band, the AP 110-2 may operate in 5 GHz frequency band, andthe AP 110-3 may operate in 6 GHz frequency band. In the embodimentdepicted in FIG. 1 , the AP MLD is connected to a distribution system(DS) 106 through a distribution system medium (DSM) 108. Thedistribution system (DS) 106 may be a wired network or a wirelessnetwork that is connected to a backbone network such as the Internet.The DSM 108 may be a wired medium (e.g., Ethernet cables, telephonenetwork cables, or fiber optic cables) or a wireless medium (e.g.,infrared, broadcast radio, cellular radio, or microwaves). Although theAP MLD 102 is shown in FIG. 1 as including three APs, other embodimentsof the AP MLD 102 may include fewer than three APs or more than threeAPs. In addition, although some examples of the DSM 108 are described,the DSM 108 is not limited to the examples described herein.

In the embodiment depicted in FIG. 1 , the non-AP MLD 104-1 includesmultiple non-AP stations (STAs) 120-1, 120-2, 120-3. The STAs 120-1,120-2, 120-3 may be implemented in hardware (e.g., circuits), software,firmware, or a combination thereof. The STAs 120-1, 120-2, 120-3 may befully or partially implemented as an IC device. In some embodiments, thenon-AP STAs 120-1, 120-2, 120-3 are wireless devices that wirelesslyconnect to wireless APs. For example, at least one of the non-AP STAs120-1, 120-2, 120-3 may be a laptop, a desktop personal computer (PC), amobile phone, or other wireless device that supports at least one WLANcommunications protocol. In some embodiments, the non-AP STAs 120-1,120-2, 120-3 are wireless devices compatible with at least one IEEE802.11 protocol (e.g., an IEEE 802.11be protocol). In some embodiments,the non-AP MLD has one Media Access Control (MAC) data serviceinterface. In an embodiment, a single address is associated with the MACdata service interface and is used to communicate on the DSM 108. Insome embodiments, the AP MLD 102 and/or the non-AP MLDs 104-1, 104-2,104-3 identify which communications links support the multi-linkoperation during a multi-link operation setup phase and/or exchangesinformation regarding multi-link capabilities during the multi-linkoperation setup phase. Each of the non-AP STAs 120-1, 120-2, 120-3 ofthe non-AP MLD may operate in a different frequency band. For example,the non-AP STA 120-1 may operate in 2.4 GHz frequency band, the non-APSTA 120-2 may operate in 5 GHz frequency band, and the non-AP STA 120-3may operate in 6 GHz frequency band. Each of the non-AP MLDs 104-2,104-3 may be the same as or similar to the non-AP MLD 104-1. Forexample, the non-AP MLD 104-2 or 104-3 includes multiple non-AP STAs. Insome embodiments, each STA includes at least one antenna, at least onetransceiver operably connected to the at least one antenna, and at leastone controller connected to the corresponding transceiver. In someembodiments, the at least one transceiver includes a PHY device. The atleast one controller operably may be configured to control the at leastone transceiver to process received packets through the at least oneantenna. In some embodiments, the at least one controller is implementedwithin a processor, such as a microcontroller, a host processor, a host,a DSP, or a CPU, which can be integrated in a corresponding transceiver.In the embodiment depicted in FIG. 1 , the non-AP MLD 104-1, 104-2, or104-3 communicates with the AP MLD 102 through multiple communicationslinks 112-1, 112-2, 112-3. For example, each of the non-AP STAs 120-1,120-2, 120-3 communicates with an AP 110-1, 110-2, or 110-3 through acorresponding communications link 112-1, 112-2, or 112-3. Although thenon-AP MLD 104-1 is shown in FIG. 1 as including three non-AP STAs,other embodiments of the non-AP MLD 104-1 may include fewer than threenon-AP STAs or more than three non-AP STAs. In addition, although the APMLD 102 communicates (e.g., wirelessly communicates) with the non-APMLDs 104-1, 104-2, 104-3 through multiple links 112-1, 112-2, 112-3, inother embodiments, the AP MLD 102 may communicate (e.g., wirelesslycommunicates) with the non-AP MLDs through more than threecommunications links or less three than communications links.

In a multi-link operation, an AP multi-link device (e.g., an AP MLD)typically broadcasts traffic indication map (TIM) information, where theTIM information includes buffered data information on one or morecommunications links. Under a single TIM configuration, a non-APmulti-link device (e.g., a STA MLD) can have multiple Association IDs(AIDs), with one AID per link. A single TIM element can include a STA inmultiple links. Under a multiple TIM configuration, each TIM correspondsto one link. Consequently, if an AP needs to indicate TIM information onmultiple links, the AP can include a separate TIM (sub)element in abeacon frame. Under both a single TIM configuration and a multiple TIMconfiguration, a TIM element indication may include an indication ofwhether there is a buffered data frame for a station (STA) andinformation regarding to which link(s) these buffered data can bedelivered if there is a buffered data frame for the STA. In case thereis no buffered data frame for a STA, the second indication (i.e.,information regarding which link buffered data can be delivered) doesnot need to be delivered. However, in a typical multi-link operation,there are generally more stations (STAs) whose TIM bit is set to zerothan STAs whose TIM bit is set to one in a beacon frame. Under bothsingle TIM and multiple TIMs configurations, more than one bit can beallocated for each STA regardless of buffered data status, andconsequently, redundant signaling overhead exists under both single TIMand multiple TIM configurations. In addition, under both single TIMconfiguration and multiple TIM configuration, extended TIM overhead mayoccur. For example, under single TIM configuration, due to increased AIDspace, the partial bitmap size of a TIM element may be longer than thepartial bitmap size of a TIM element under a single link case. Under amultiple TIM configuration, a beacon frame needs to include multiple TIM(sub)elements, which can cause TIM overhead.

In some embodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to operate under a single TIM configuration to maintainbackward compatibility and allocate one Association ID (AID) perassociation. In an embodiment, the AP MLD is configured to allocate oneAID per STA MLD. For example, the AP MLD allocates one AID to the non-APMLD 104-1. Each of the non-AP STAs 120-1, 120-2, 120-3 of the non-AP MLD104-1 may have the same AID as the non-AP MLD 104-1. However, it doesnot preclude a STA MLD from having more than one AID. In an embodiment,regardless of a specific communications link within the AP MLD, as longas there is buffered data for a STA MLD (e.g., the non-AP MLD 104-1),the AP MLD is configured to set a TIM bit corresponding to the STA MLDto a specific value (e.g., 1). In addition to TIM information thatindicates buffered data for a STA MLD (e.g., the non-AP MLD 104-1), theAP MLD is configured to define a link indication element to indicate inwhich communications link associated with the STA MLD buffered data isto be delivered. For example, the AP MLD may set a component of the linkindication element, which corresponds to the communications linkassociated with the STA MLD in which the buffered data is to bedelivered, to a specific value (e.g., 1).

In some embodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to define a link mapping bitmap (LMB) per AID, where each bitwithin the LMB per AID indicates a designated communications link withina STA MLD (e.g., the non-AP MLD 104-1) corresponding to the AID. In someembodiments, each bit within the LMB per AID indicates a set ofdesignated communications links within a STA MLD (e.g., the non-AP MLD104-1) corresponding to the AID. Before an AP MLD transmits a data frameto a STA MLD, the AP MLD indicates the size of the LMB per AID and whichcommunications link corresponds to which bit within the LMB per AID ofthe STA MLD. This indication can be done during a multi-link associationprocess. In some embodiments, the indication information is broadcastedin a beacon frame. In some embodiments, the indication information isindicated by a probe response frame or a (Re)association response frame.The AP MLD can allocate one or more AIDs to a STA MLD for a multi-linkassociation. In some embodiments, in normal operation, the AP MLD isconfigured to assign a single AID to a STA MLD. However, in somesituations, the AP MLD may assign more than one AID to a STA MLD. Insome embodiments, the AP MLD is configured to assign multiple AIDs to aSTA MLD if the number of communications links that the AP MLD supportsis more than the size of the LMB per AID. For example, if the AP MLDsupports 8 links and the AP MLD maintains an LMB per AID of 2 bits(i.e., 4 links per LMB per AID), the AP MLD may assign two AIDs to eachSTA MLD.

In some embodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to transmit a frame (e.g., a beacon frame) containing asingle TIM element. Each bit in the TIM element may correspond totraffic buffered for a non-AP MLD that the AP MLD with which an AP isaffiliated is prepared to deliver when the frame (e.g., a beacon frame)is transmitted. In an embodiment, bit number N indicates the status ofbuffered, individually addressed MAC Protocol Data Units (MPDUs)/MACProtocol Data Units (MMPDUs) for a STA or a non-AP MLD whose AID is N,or group addressed MSDUs/MMPDUs for STAs whose group AID is N.

In some embodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to transmit a frame (e.g., a beacon frame) containing asingle TIM to a STA MLD (e.g., the non-AP MLD 104-1). In an embodiment,the AP MLD 102 is configured to set, for each AID, a corresponding TIMbit to a specific value (e.g., 1) if there is buffered data for the AIDregardless of the specific communications link associated with a STA MLDthat is mapped to the AID in which the buffered data is to be delivered.In addition to the TIM element (e.g., transmitted subsequently to theTIM element), the AP MLD 102 is configured to define a buffered data tolink mapping (BLM) element. The BLM element may include a link mappingbitmap (LMB). In some embodiments, the size of the LMB is represented asN_TIM*N_bitmap, where N_TIM denotes the number of AIDs whosecorresponding TIM bit is set to a specific value (e.g., 1), whichindicates there is buffered data to be delivered to a STA MLD having theAID, and N_bitmap denotes the size of LMB per AID. In some embodiments,the location of LMB per AID is predefined. For example, an LMB is listedin monotonically increasing order of LMB per AID for those AIDs whoseTIM bit is set to a specific value (e.g., 1), indicating there isbuffered data to be delivered to the AID. In some embodiments, a STA MLD(e.g., the non-AP MLD 104-1) identifies that the AP MLD 102 has bufferedframes for the STA MLD by identifying that a TIM element received fromthe AP MLD contains a TIM bit corresponding to the STA MLD's AID that isset to a specific value (e.g., 1). In some embodiments, when a STA MLD(e.g., the non-AP MLD 104-1) identifies in a TIM element received fromthe AP MLD containing a TIM bit corresponding to the STA MLD's AID isset to 1, the STA MLD further checks the LMB corresponding to the AIDand identifies specific communications link(s) that the buffered trafficis to be delivered.

FIG. 2 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.According to the method, at block 202, at an AP multi-link device,Association IDs (AIDs) are allocated to non-AP multi-link devices byallocating one of the AIDs to each of the non-AP multi-link devices. Atblock 204, at the AP multi-link device, a first indication element forthe AIDs is generated to indicate a buffered data configuration at theAP multi-link device for the non-AP multi-link devices. The APmulti-link device may generate a second indication element to indicatecommunications link information associated with the buffered dataconfiguration at the AP multi-link device. For example, the APmulti-link device may generate a link mapping bitmap (LMB) for each ofthe AIDs whose corresponding non-AP multi-link device the AP multi-linkdevice has a buffered data unit to be delivered to. The LMB may indicateone or more designated communications links (e.g., a set of designatedcommunications links) through which the buffered data unit is to bedelivered. The buffered data unit may be an individually addressedbuffered data unit. The AP multi-link device may transmit the firstindication element and the second indication element to the non-APmulti-link devices in a broadcast frame, which may be a beacon frame.The AP multi-link device may generate an LMB only for each of the AIDswhose corresponding non-AP multi-link device the AP multi-link devicehas an individually addressed buffered data unit to be delivered to. TheLMB may indicate one or more designated communications links (e.g., adesignated set of communications links) through which the individuallyaddressed buffered data unit is to be delivered. The AP multi-linkdevice, may, for each AID of the AIDS, set a corresponding trafficindication map (TIM) component to a specific value when the APmulti-link device has buffered data to be delivered to a correspondingnon-AP multi-link device to which the AID is allocated. In someembodiments, the corresponding TIM component includes a TIM bit, and thespecific value is 1. In some embodiments, the buffered dataconfiguration at the AP multi-link device includes information regardingan individually addressed buffered data unit and a group addressedbuffered data unit at the AP multi-link device. The AP multi-link devicemay generate a traffic indication map (TIM) that includes a firstsection containing information regarding the individually addressedbuffered data unit and a second section containing information regardingthe group addressed buffered data. The first and second sections mayhave non-overlapping AID ranges within the AIDs. In some embodiments,the AP multi-link device and the non-AP multi-link devices arecompatible with an IEEE 802.11 protocol. The AP multi-link device may besimilar to, the same as, or a component of the AP MLD 102 depicted inFIG. 1 . The non-AP multi-link devices may be similar to, the same as,or a component of the non-AP MLDs 104-1, 104-2, 104-3 depicted in FIG. 1.

FIG. 3 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.According to the method, at block 302, at a non-AP multi-link device, aframe that indicates or includes one AID that is assigned to the non-APmulti-link device, is received from an AP multi-link device. At block304, at the non-AP multi-link device, a first indication element thatindicates a buffered data configuration at the AP multi-link device forthe non-AP multi-link device based on the AID is received. At block 306,at the non-AP multi-link device, whether the AP multi-link device hasbuffered data for the non-AP multi-link device based on the firstindication element is determined. In some embodiments, the non-APmulti-link device receives a second indication element that indicatescommunications link information associated with the buffered dataconfiguration at the AP multi-link device and determines one or morecommunications links (e.g., a set of communications links) through whichthe buffered data is delivered based on the second indication element.The second indication element may include an LMB that indicates thecommunications link(s) through which the buffered data is to bedelivered. The buffered data unit may be an individually addressedbuffered data unit. The non-AP multi-link device may receive the firstindication element from a broadcast frame from the AP multi-link device.In some embodiments, the first indication element includes a TIMcomponent that is set to a specific value when the AP multi-link devicehas buffered data to be delivered to the non-AP multi-link device. Insome embodiments, the buffered data configuration at the AP multi-linkdevice includes information regarding an individually addressed buffereddata unit and a group addressed buffered data unit at the AP multi-linkdevice. The first indication element may include a traffic indicationmap (TIM) that includes a first section containing information regardingthe individually addressed buffered data unit and a second sectioncontaining information regarding the group addressed buffered data. Thefirst and second sections may have non-overlapping AID ranges. In someembodiments, the AP multi-link device and the non-AP multi-link devicesare compatible with an IEEE 802.11 protocol. The AP multi-link devicemay be similar to, the same as, or a component of the AP MLD 102depicted in FIG. 1 . The non-AP multi-link device may be similar to, thesame as, or a component of the non-AP MLDs 104-1, 104-2, 104-3 depictedin FIG. 1 .

FIG. 4 depicts a TIM bitmap 410 and a corresponding link mapping bitmap(LMB) 420 that can be used in a multi-link operation by the multi-linkcommunications system 100 depicted in FIG. 1 . In the example depictedin FIG. 4 , the AP MLD 102 is associated with 256 STA MLDs and supportsthree communications links. The AP MLD 102 generates the TIM bitmap forthe associated 256 STA MLDs with different AIDs and the LMB for STA MLDsfor which the AP MLD has buffered data. As depicted in FIG. 4 , each LMBper AID is composed of three bits and each communications link (e.g.,first link, second link, or third link) corresponds to a respective bit(e.g., first bit, second bit, or third bit) of the LMB per AID. Out ofthe 256 STA MLDs, the AP MLD has buffered data for 5 STA MLDs, whichhave corresponding AIDs, 12, 28, 35, 57, and 77. The size of the LMB isonly 15 bits (i.e., 5 STAs×3 bit per STA), instead of 756 bits for allof the 256 STA MLDs.

In some embodiments, buffered data to link mapping does not include abitmap. For example, if the size of the LMB per AID is N bits (N beingan integer), it can indicate 2^(N) different states or different linkcombinations. If the LMB per AID is a simple bitmap, it can indicatestate [0,,,0] , which implies there is no communications link to deliverthe buffered data. As the LMB per AID is used only for those AIDs towhich buffered data are to be delivered, at least one communicationslink should be indicated. Therefore, this state [0,,,0] may neverhappen, and this state is wasted. To deal with this problem, in someembodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to indicate a corresponding communications link combinationfor each of 2^(N) states of LMB per STA MLD. In some embodiments, thestate [0,,,0] has a special implication, such as, a communications linkwill be selected per a STA MLD's request, a special transmission scheme(e.g., multi-AP joint transmission) is expected, or the use of apredetermined communications link.

In some embodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to define an LMB per AID, not an LMB per STA MLD. Forexample, if a STA MLD (e.g., the non-AP MLD 104-1) is assigned more thanone AID by the AP MLD 102, the AP MLD 102 is configured to define morethan one LMB for the STA MLD. If one AID (e.g., a broadcast AID)corresponds to more than one STA MLD, the more than one STA MLD thatcorrespond to the AID need to check the LMB for buffered data status. Insome embodiments, the size of the LMB is a multiple of octets. IfN_TIM*N_bitmap (where N_TIM denotes the number of AIDs whosecorresponding TIM bit is set to a specific value (e.g., 1), indicatingthere is buffered data to be delivered to the AIDs, and N_bitmap denotesthe size of LMB per AID) is not a multiple of 8, the AP MLD 102 may setthe size of LMB to the smallest number that is a multiple of 8 and thatis greater than N_TIM*N_bitmap.

In some embodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to set the size of LMB per AID different for various AIDs. Inan embodiment, the AP MLD may indicate a different bitmap size fordifferent LMB per AID groups. For example, the AP MLD may determine thatan LMB per AID includes N1 bit(s) if an AID is in the range of [0,,,M1],that an LMB per AID includes N2 bit(s) if an AID is in the range of[M1+1,,, M2], where N1, N2, M1, M2 are positive integers, and so on.When a STA MLD (e.g., the non-AP MLD 104-1) identifies that itscorresponding TIM bit is set to a specific value (e.g., 1), the STA MLDcalculates a location of the LMB per AID for the STA MLD within the LMBas follows. If those AIDs whose corresponding TIM bit is set to aspecific value (e.g., 1) are within the range of [0,,,M1], N1 isconsidered in calculating the bitmap size, and if those AIDs whosecorresponding TIM bit is set to 1 are within the range of [M1+1,,,M2],N2 is considered in calculating the bitmap size. In some embodiments, inthe case in which the AP MLD supports a particular number (e.g., 3) ofcommunications links but most of the STA MLDs support a smaller number(e.g., only 2) of communications links while a small number of STA MLDssupport the particular number (e.g., 3) of links, the AP MLD configuresAIDs as two groups. For example, for group 1 AID, the size of LMB perAID is 2 bits, and the AID range is [0,,,800], while for group 2 AID,the size of LMB per AID is 3 bits, and the AID range is [801,,,1000].For a STA MLD that supports only 2 communications links, the STA MLD isindicated as a Group 1 member, while for a STA MLD that supports 3communications links, the STA MLD is indicated as a Group 2 member. Inanother example, for group 1 AID, the size of the LMB per AID is 2 bits,and the AID range is [0,,,800], while for group 2 AID, the size of theLMB per AID is 1 bit, and the AID range is [801,,,1000]. For a STA MLDthat supports only 2 communications links, the STA MLD is indicated as aGroup 1 member, while for a STA MLD that supports 3 communicationslinks, the STA MLD is indicated as both a Group 1 and Group 2 member,and 2 AIDs are allocated for the STA MLD (one from each group).

FIG. 5 depicts an example information element format for a buffered datato link mapping (BLM) element 512 that can be used in a multi-linkoperation by the multi-link communications system 100 depicted in FIG. 1. In the example depicted in FIG. 5 , the BLM element includes anelement ID field 514 (e.g., 1 octet) that may contain identificationinformation which specific element this element represents, a lengthfield 516 (e.g., 1 octet) that may contain element length information,an element ID extension field 518 (e.g., 1 octet) that may include IDextension information, and a Link Mapping Bitmap (LMB) field 520, whichmay contain information regarding a communications link for deliveringbuffered data and have variable size. In some embodiments, the BLMelement further includes some reserved (sub)field.

FIG. 6 depicts another example information element format for a BLMelement 612 that can be used in a multi-link operation by the multi-linkcommunications system 100 depicted in FIG. 1 . Compared to the BLMelement 512 depicted in FIG. 5 , the BLM element 612 depicted in FIG. 6includes an additional bitmap control data field 622. Specifically, inthe example depicted in FIG. 6 , the BLM element includes an element IDfield 614 (e.g., 1 octet) that may contain identification informationwhich specific element this element represents, a length data field 616(e.g., 1 octet) that may contain element length information, an elementID extension field 618 (e.g., 1 octet) that may include ID extensioninformation, an LMB field 620, which may contain information regarding acommunications link for delivering buffered data and have variable size,and the bitmap control data field (e.g., M octet(s), where M is apositive integer). The bitmap control data field may contain controlinformation regarding the configuration of LMB, where some examples ofsuch control information may include the number of AID groups, size ofeach LMB per AID within the LMB for each AID group, the number of LMBsper AID within the LMB for each AID group, the range of AIDs for eachAID group, and/or reserved (sub)field.

FIG. 7 depicts another example information element format for a BLMelement 712 that can be used in a multi-link operation by the multi-linkcommunications system 100 depicted in FIG. 1 . Compared to the BLMelement 612 depicted in FIG. 6 , the BLM element 712 depicted in FIG. 7includes an LMB field 720 that contains a direct indication of AID andLMB per AID for each AID. Specifically, in the example depicted in FIG.7 , the BLM element includes an element ID field 714 (e.g., 1 octet)that may contain identification information which specific element thiselement represents, a length field 716 (e.g., 1 octet) that may containelement length information, an element ID extension field 718 (e.g., 1octet) that may include ID extension information, and the LMB field 720,which may contain information regarding a communications link fordelivering buffered data and have variable size. Instead of relying onthe TIM element to identify the location of the LMB per AID for eachAID, the LMB data field contains a direct indication of AID and LMB perAID for each AID.

FIG. 8 depicts another example information element format for a BLMelement 812 that can be used in a multi-link operation by the multi-linkcommunications system 100 depicted in FIG. 1 . Compared to the BLMelement 712 depicted in FIG. 7 , the BLM element 812 depicted in FIG. 8includes an additional bitmap control field 822. Specifically, in theexample depicted in FIG. 8 , the BLM element 812 includes an element IDfield 814 (e.g., 1 octet) that may contain identification informationwhich specific element this element represents, a length field 816(e.g., 1 octet) that may contain element length information, an elementID extension field 818 (e.g., 1 octet) that may include ID extensioninformation, an LMB field 820 that allows a different bitmap size, andthe bitmap control field (e.g., M octet(s), where M is a positiveinteger). The bitmap control field may contain control informationregarding the configuration of LMB, where some examples of such controlinformation may include the number of AID groups, size of each LMB perAID within LMB for each AID group, the number of LMB per AID within theLMB for each AID group, the range of AIDs for each

AID group, and/or reserved (sub)field.

In some embodiments, using a Link Mapping bitmap (LMB) to represent abuffered data to link mapping (BLM) element may introduce overhead. Whena BLM element includes an LMB, the size of the LMB can be represented asN_TIM*N_bitmap, where N_TIM denotes the number of AIDs whosecorresponding TIM bit is set to a specific value (e.g., 1), and N_bitmapdenotes the size of LMB per AID (LMBperAID). If there are legacy STAs ora single-link STA associated with an AP multi-link device (MLD) as thereis only one communications link for those STAs, the AP MLD does not needto indicate a specific communications link to use for retrieving thebuffered data. Consequently, the legacy or the single-link STAs may notcheck a BLM element even if the BLM element is included in a beaconframe. In addition, in a BLM element that includes an LMB, if thelocation of the “LMBperAID” for a specific non-AP MLD is determinedimplicitly (e.g., without explicit AID indication), every STA needs tohave the same size of the LMBperAID. LMBperAID for legacy STAs orsingle-link STAs needs to have the size of N_bitmap, which givesnon-necessary indication overhead.

In some embodiments, a buffered data to link mapping (BLM) elementincludes a first field indicating information on an AID that correspondsto the first LMBperAID in a corresponding Link Mapping bitmap (LMB) andthe corresponding LMB. The information on an AID can be indicated inmultiple different ways, which include (but not limited to), AID thatcorresponds to the first LMBperAID, the highest AID that corresponds toa bit position in the partial virtual bitmap of a corresponding TIMelement that the LMBperAID is skipped, the Lowest AID that correspondsto a bit position in the partial virtual bitmap of the corresponding TIMelement that is considered in deriving the LMBperAID, and the number ofa specific value (e.g., “1”) in the partial virtual bitmap of thecorresponding TIM element (e.g., in the front of the bitmap) that theLMBperAID is skipped. In some embodiments, the corresponding LMBincludes a union of LMBperAID for those AIDs that the partial virtualbitmap of the corresponding TIM element is set to a specific value(e.g., 1), which indicates buffered data to be delivered from an AP MLLEor an AP MLD, from the AID indicated by the first field. In an exampleoperation, an AP MLD (e.g., the AP MLD 102) or an AP MLD, maintains twogroups of AIDs, i.e., a first group of AIDs and a second group of AIDs.The first group of AIDs may correspond to STAs that do not supportmulti-link capability, STAs that operate on a single-link, STAs thatsupport multi-link operation but only one communications link isenabled, and/or STAs that all traffic identifiers (TIDs) are mapped toall setup links. The second group of AIDs may correspond to STAs thatsupport multi-link operation, STAs that have more than one link setupwith the AP MLLE or the AP MLD, STAs that have more than onecommunications link enabled, and/or STAs that specific TID-to-linkmapping has been negotiated with the AP MLLE or the AP MLD. The highestAID of the first group of AIDs may be smaller than the lowest AID of thesecond group of AIDs. In some embodiments, the first field indicates anAID that is equal to or smaller than the lowest AID of the second groupof AIDs. In addition, the first field may be higher than the highest AIDof the first group of AIDs.

FIG. 9 depicts a TIM bitmap 910 and a corresponding link mapping bitmap(LMB) 920 that can be used in a multi-link operation by the multi-linkcommunications system 100 depicted in FIG. 1 . In the example depictedin FIG. 9 , an AP multi-link device (e.g., the AP MLD 102) is associatedwith 256 STA MLDs and supports four communications links. The AP MLD 102may generate the TIM bitmap for the associated 256 STA MLDs withdifferent AIDs and the LMB for STA MLDs for which the AP MLD 102 or acorresponding AP MLD has buffered data. As depicted in FIG. 9 , each LMBper AID is composed of two bits. AID 1-30 are assigned to legacy STAsand single-link STAs, while AID 31-255 are assigned to non-AP MLLEs orMLDs. Out of the 256 STA MLDs, the AP MLD 102 or a corresponding AP MLDhas buffered data for 5 STA MLDs, which have corresponding AIDs, 12, 28,35, 57, and 77. AID 12 and AID 28 are of legacy STAs and AIDs 35, 57, 77are of non-AP MLDs or MLDs. The size of the LMB goes down to only 6 bits(i.e., 3 non-AP MLD or MLD×2 bit per non-AP MLD).

In some embodiments, a buffered data to link mapping (BLM) elementincludes the number of LMBperAID in a corresponding link mapping bitmap(LMB) and the corresponding LMB. The LMB may be a union of LMBperAID forthose AIDs that the partial virtual bitmap of a corresponding TIMelement is set to a specific value (e.g., 1), which indicates buffereddata to be delivered from an AP MLLE or an AP MLD, which may be from theAID indicated by the first field. In an example operation, an AP MLLE oran AP MLD, maintains two groups of AIDs, i.e., a first group of AIDs anda second group of AIDs. The first group of AIDs may correspond to STAsthat do not support multi-link capability, STAs that operate on asingle-link, STAs that support multi-link operation but only onecommunications link is enabled, or STAs that all TIDs are mapped to allsetup links. The second group of AIDs may correspond to STAs thatsupport multi-link operation, STAs that have more than one link setupwith the AP MLD, STAs that have more than one communications linkenabled, STAs that specific TID-to-link mapping has been negotiated withthe AP MLLE or the AP MLD. The lowest AID of the first group of AIDs maybe higher than the highest AID of the second group of AIDs. In someembodiments, the number of LMBperAID indicates a number that is equal to(or greater than) the number of AIDs within the second group of AIDsthat a bit in the partial virtual bitmap of a corresponding TIM elementis set to a specific value (e.g., 1), indicating buffered data to bedelivered from an AP MLLE or an AP MLD.

FIG. 10 depicts a TIM bitmap 1010 and a corresponding link mappingbitmap (LMB) 1020 that can be used in a multi-link operation by themulti-link communications system 100 depicted in FIG. 1 . In the exampledepicted in FIG. 10 , an AP multi-link device (e.g., the AP MLD 102) isassociated with 256 STA MLDs and supports four communications links. TheAP MLD 102 may generate the TIM bitmap for the associated 256 STA MLDswith different AIDs and the LMB for STA MLDs for which the AP MLD 102has buffered data. As depicted in FIG. 10 , each LMB per AID is composedof two bits. AID 1-50 are assigned to non-AP MLLEs or MLDs, while AID51-255 are assigned to legacy STAs and single-link STAs. Out of the 256STA MLDs, the AP MLD 102 or a corresponding AP MLD has buffered data for5 STA MLDs, which have corresponding AIDs, 12, 28, 35, 57, and 77. AID12, AID 28 and AID 35 are for non-AP MLLEs or MLDs and AIDs 57, 77 arefor legacy STAs. The size of the LMB is 6 bits (i.e., 3 non-AP MLLE orMLD×2 bit per non-AP MLLE or MLD).

In some embodiments, in a TIM element, a first N bits of the partialvirtual bitmap indicates if one or more group addressed MAC ProtocolData Units (MPDUs)/MAC Protocol Data Units (MMPDUs) are buffered at acorresponding AP. These N bits may not correspond to specific AIDs.Consequently, the first N bits that correspond to group addressedMSDUs/MMPDUs may need to be considered differently in link mappingcompared to unicast MSDUs/MMPDUs. In some embodiments, an LMB does notinclude an LMBperAID for those AIDs that correspond to the groupaddressed MSDUs/MMPDUs in the partial virtual bitmap of a correspondingTIM element. If a buffered data to link mapping (BLM) element includes afirst field indicating information on an AID that corresponds to thefirst LMBperAID in a corresponding Link Mapping bitmap (LMB) and thecorresponding LMB, and the first N bits of the partial virtual bitmap isused for the indication of the group addressed frames, the first fieldshall indicate an AID that is greater than N. In some embodiments, thenumber of bits for LMBperAID for AIDs that correspond to the groupaddressed frames is indicated. In some embodiments, the number of bitsfor LMBperAID for AIDs that correspond to the group addressed frames maybe equal to the number of bits for LMBperAID for individually addressedframes. In some other embodiments, the number of bits for LMBperAID forAIDs that correspond to the group addressed frames may be different fromthe number of bits for LMBperAID for individually addressed frames.

In a conventional TIM element, the bits 1 to 2^(N)−1 of the bitmap areused to indicate that one or more group addressed frames, which arebuffered for each AP corresponding to a non-transmitted basic serviceset identifier (BSSID). As the bit 0 of the bitmap is used to indicatethe group addressed frames corresponding to a transmitted BSSID, thebits 0 to 2^(N)−1 of the bitmap are used to indicate the group addressedframes. If an AP MLLE or MLD supports more than one communications link,and there is more than one AP affiliated with the AP MLLE or MLD on acommunications link, it may not be clear how to indicate the groupaddressed frames on other communications links.

In some embodiments, in a TIM element that is transmitted on a firstcommunications link, a first N1 (N1 being a positive integer) bits of apartial virtual bitmap indicate if one or more group addressedMSDUs/MMPDUs are buffered at an AP multi-link device (e.g., the AP MLD102) on the first communications link. Bit 0 of the partial virtualbitmap may correspond to the transmitted BSSID of the AP MLD on thefirst communications link. Bits 1-(N1−1) of the partial virtual bitmapmay correspond to the non-transmitted BSSID of the AP MLD on the firstcommunications link.

In some embodiments, in a TIM element, a first N bits of a partialvirtual bitmap indicate if one or more group addressed MSDUs/MMPDUs arebuffered at an AP multi-link device (e.g., the AP MLD 102). Each bitstarting from bit N in the traffic indication virtual bitmap maycorrespond to individually addressed traffic buffered for a specific STAor non-AP MLD within any basic service set (BSS) corresponding to atransmitted or non-transmitted BSSID at the time a corresponding beaconframe is transmitted. Each bit within the first N bits may indicate ifone or more group addressed frames are buffered at each different APaffiliated with the AP MLD. Different APs can be of a transmitted BSSID.Different APs can be of a non-transmitted BSSID. Different APs can be onthe same communications link on which a corresponding beacon frame thatcarries the TIM element is transmitted. Different APs can be ondifferent communications links from the communications link in which acorresponding beacon frame that carries the TIM element is transmitted.In an example operation, an AP multi-link device (e.g., the AP MLD 102)supports two communications links, i.e., link0 and link1. There may be 7non-transmitted BSSIDs on link0 of the AP MLD, while there may be 3non-transmitted BSSIDs on link1 of the AP MLD. The first 12 bits of theAIDs may be allocated for group addressed frames. For a TIM elementtransmitted on link0, AID0 corresponds to transmitted BSSID on link0,AIDs 1-7 correspond to non-transmitted BSSID on link0, AID8 correspondsto transmitted BSSID on link1, and AIDs 9-11 correspond tonon-transmitted BSSID on link1. For a TIM element transmitted on link1,AID0 corresponds to transmitted BSSID on link1, AIDs 1-3 correspond tonon-transmitted BSSID on link1, AID4 corresponds to transmitted BSSID online0, and AIDs 5-11 correspond to non-transmitted BSSID on link0.

In some embodiments, in a TIM element, a first N_link*2^(K) bits (whereN, K are positive integers) of a partial virtual bitmap indicates if oneor more group addressed MSDUs/MMPDUs are buffered at an AP multi-linkdevice (e.g., the AP MLD 102), where N_link denotes the number ofcommunications links that the AP MLD supports. For i-th, the AP MLD mayhave 2^((n_i))−1 non-transmitted BSSIDs and K is equal to (or greaterthan) max(n_i). In some embodiments, bit 0 of the partial virtual bitmapcorresponds to the transmitted BSSID of the AP MLD on the communicationslink that the TIM element is carried. Bit m*2^(K) (1<=m<=N_link-1) ofthe partial virtual bitmap may correspond to the transmitted BSSID ofthe AP MLD on the communications link that the TIM element is notcarried. The bit positions that are not mapped to specific BSSID of theAP MLD may be reserved and set to 0. In an example operation, an AP MLDsupports two communications links, i.e., link0 and link1. There may be 7non-transmitted BSSIDs on link0 of the AP MLD (n0=3), while there may be3 non-transmitted BSSIDs on link1 of the AP MLD (n1=2). Subsequently,N_link=2 and K=max(2,3)=3. Consequently, the first 16 bits of the AIDsare allocated for group addressed frames. For a TIM element transmittedon link0, AID0 corresponds to transmitted BSSID on link0, AIDs 1-7correspond to non-transmitted BSSID on link0, AID8 corresponds totransmitted BSSID on link1, AIDs 9-11 correspond to non-transmittedBSSID on link1, and AIDs 12-15 correspond to no BSSID and are set to 0.For a TIM element transmitted on link1, AID0 corresponds to transmittedBSSID on link1, AIDs 1-3 correspond to non-transmitted BSSID on link1,AIDs 4-7 correspond to no BSSID and are set to 0, AID8 corresponds totransmitted BSSID on link0, and AIDs 9-15 correspond to non-transmittedBSSID on link0.

In some embodiments, in a TIM element that is transmitted on a firstcommunications link, a first N1 bits of a partial virtual bitmapindicate if one or more group addressed MSDUs/MMPDUs are buffered at anAP multi-link device (e.g., the AP MLD 102) on the first communicationslink. Bit 0 of the partial virtual bitmap may correspond to thetransmitted BSSID of the AP MLD on the first communications link. Bit1—(N1-1) of the partial virtual bitmap may correspond to thenon-transmitted BSSID of the AP MLD on the first communications link.The AP MLD may explicitly indicate the bit position in the partialvirtual bitmap for an AP affiliated with the AP MLD on a communicationslink that is different from the first communications link.

IEEE 802.11be protocol defines a directional-based TID-to-link mappingmechanism among the setup links of a multi-link device (MLD). Bydefault, after the multi-link setup, all TIDs are mapped to all setuplinks. The multi-link setup may include the TID-to-link mappingnegotiation. TID-to-link mapping can have the same or different link-setfor each TID unless a non-AP MLD indicates that it requires to use thesame link-set for all TIDs during the multi-link setup phase. TheTID-to-link mapping can be updated after multi-link setup through anegotiation, which can be initiated by any MLD. When the responding MLDcannot accept the update, it can reject the TID-to-link mapping update.Therefore, depending on TID-to-link mapping, TIM indication may need tobe different. If all TIDs are mapped to all setup links, there is noneed to indicate additional TID-to-link mapping. If there is specificTID-to-link mapping configured, a beacon frame needs to have TID-to-linkmapping information. In some embodiments, an AP multi-link device (e.g.,the AP MLD 102) indicates if a bit in a partial virtual bitmap of a TIMelement transmitted on a communications link indicates if anyindividually addressed buffered units (BUs) for a non-AP multi-linkdevice (e.g., the non-AP MLD 104) are buffered by the AP MLD or by an APaffiliated with the AP MLD on the communications link.

When a non-AP MLD (e.g., the non-AP MLD 104) associates with an AP MLD(e.g., the AP MLD 102), one of APs affiliated with the AP MLD mayindicate in a beacon frame if the AP MLD has buffered data to bedelivered to the non-AP MLD. The indication may use a TIM element in thebeacon frame and/or additional element. The information in a beaconframe may include information regarding whether or not an AP MLD hasbuffered data to be delivered to a non-AP MLD and/or informationregarding which communications link is to be used for the delivery ofthe buffered data. If a station (STA) affiliated with a non-AP MLDreceives a beacon frame and identifies that a corresponding AP MLD hasbuffered data on one or more links, the non-AP MLD can indicate thatSTAs affiliated with the non-AP MLD corresponding to the one or morelinks are in an awake state and initiate downlink transmission from theAP MLD, which can be done by sending a frame, such as, a PS-Poll frame,a QoS Null frame, etc. The frame sent on one communications link canindicate the awake state of other STAs affiliated with the non-AP MLD.

When a STA affiliated with a non-AP MLD sends a frame, the STA may alsoindicate its (preferred) status of each STA within the non-AP MLD. Forexample, each bit in a link bitmap may indicate that the STA in thecorresponding link is in an awake state or a doze state (e.g., a powersaving state). After receiving a TIM indication from a corresponding APMLD, the non-AP MLD may transmit a frame, such as, a PS-Poll frame or aQoS Null frame, where the frame includes the link bitmap indicatingwhich STA(s) will be in awake and which STA(s) will be in doze state.After receiving the frame from the STA, the AP MLD transmits downlinkframes only on the communications link that the STA is in awake state.

For a multi-link operation, one or more communications links can bemapped to each traffic identifier (TID). When an AP MLD sends TIMinformation in a beacon frame, a bit within a TIM bitmap correspondingto a non-AP MLD of a communications link is set to a specific value(e.g., 1) if the AP MLD has buffered data of any TID for the non-AP MLDon the communications link. If a TID is mapped to more than onecommunications link, and if an AP MLD has buffered data of the TID for anon-AP MLD, a bit within the TIM bitmap of all the link mapped to theTID for the non-AP MLD is set to a specific value (e.g., 1). If N (N>1)links are mapped to a TID, the non-AP MLD can send a frame indicatingthat less than N STAs affiliated with the non-AP MLD are in awake stateto save power consumption. However, if only one communications link ismapped to a TID, the non-AP MLD needs to send a frame indicating thatthe STA corresponding to the link is in awake state. However, a TIMbitmap may not contain information on buffered data's TID. If differentTIDs are mapped to different communications links, and there arebuffered data from more than one TID in the AP MLD side, it may bedifficult for a non-AP MLD to decide which communications link to stayin the doze state. For example, for an AP MLD that has 3 links—[A, B,C], a non-AP MLD TID0/1/2/3 are mapped to [A,B,C]/[A]/[B]/[C]. In thisexample, if the AP MLD has buffered data of TID0, the TIM bitmap forlinks A/B/C for the non-AP MLD is set to a specific value (e.g., 1). Thenon-AP MLD may set some of communications links to doze state. If the APMLD has buffered data of TID1, TID2, and TID3, the TIM bitmap for linksA/B/C for the non-AP MLD is set to a specific value (e.g., 1). If thenon-AP MLD sets some of communications links to doze state, the non-APMLD cannot receive the buffered data units corresponding to the TID.Therefore, for the same TIM bit setting, the non-AP STA may need to actdifferently. Without knowing TID information, the non-AP STA cannot setany of links to doze state.

In some embodiments, an AP multi-link device (e.g., the AP MLD 102) isconfigured to include TID information that the AP MLD has a buffereddata unit for a non-AP multi-link device (e.g., the non-AP MLD 104) inan AP MLD's broadcast frame (such as a beacon frame). When the non-APMLD 104 identifies the TID information indicating that the AP MLD has abuffered data unit for the non-AP MLD, the non-AP MLD may send a frameindicating which STA(s) affiliated with the non-AP MLD will be in awakestate. In some embodiments, the AP MLD is configured to include a TIMbitmap having a TIM bit that is set to 1 if the AP MLD has buffered datafor a corresponding non-AP MLD in a broadcast frame. For those non-APMLD whose TIM bit is set to 1, another field (e.g., another bitmap) maybe included to indicate the combination of TIDs for that the AP MLD hasbuffered data. In some embodiments, the field may include a TID bitmap,which is a list of bitmaps for each non-AP MLDs that the TIM bit is setto 1. In some embodiments, each state may indicate the buffered datastatus of a group of TIDs. For example, more than one TID may be mappedto a specific bit within a bitmap for a non-AP MLD. In some embodiments,the AP MLD is configured to maintain a TID bitmap of 4 bits for eachnon-AP MLD, and the k-th bit of the bitmap indicates the status ofTID_(2k), and TID_(2k+1). When the non-AP MLD sends a frame indicatingwhich STA(s) affiliated with the non-AP MLD will be in awake state, thenon-AP MLD may set at least one STA in awake state for each indicatedTID for which the AP MLD has buffered data.

FIG. 11 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.According to the method, at block 1102, at an AP multi-link device,communications links that are affiliated with the AP multi-link deviceare mapped to traffic identifiers (TIDs) for a non-AP multi-link device.At block 1104, at the AP multi-link device, an indication element toindicate that the AP multi-link device has buffered data for a first TIDof the TIDs for the non-AP multi-link device is generated. At block1106, the indication element is transmitted from the AP multi-linkdevice to the non-AP multi-link device. In some embodiment, theindication element is broadcasted from the AP multi-link device in abroadcasting frame, which may be a beacon frame. In some embodiments,the AP multi-link device receives a station operation status indicationfrom the non-AP multi-link device. The station operation statusindication may contain information regarding which station affiliatedwith the non-AP multi-link device is to be in an awake state. In someembodiments, the buffered data is transmitted from the AP multi-linkdevice to the non-AP multi-link device through one of the communicationslinks that corresponds to the first TID when a station of the non-APmulti-link device operating on the one of the communications linksassociated with the first TID is to be in the awake state. The APmulti-link device may set a corresponding traffic indication map (TIM)component of the non-AP multi-link device to a specific value. Forexample, the corresponding TIM component includes a TIM bit, and thespecific value is 1. In some embodiments, the indication elementincludes a bitmap. In some embodiments, the AP multi-link devicetransmits the buffered data to the non-AP multi-link device through oneof the communications links that does not correspond to the first TIDwhen no station of the non-AP multi-link device operating on any of thecommunications links associated with the first TID is to be in an awakestate. In some embodiments, the AP multi-link device and the non-APmulti-link devices are compatible with an IEEE 802.11 protocol. The APmulti-link device may be similar to, the same as, or a component of theAP MLD 102 depicted in FIG. 1 . The non-AP multi-link devices may besimilar to, the same as, or a component of the non-AP MLDs 104-1, 104-2,104-3 depicted in FIG. 1 .

FIG. 12 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.According to the method, at block 1202, at a non-AP multi-link device,an indication element that indicates an AP multi-link device havingbuffered data of a traffic identifier (TID) for the non-AP multi-linkdevice is received. In some embodiments, the non-AP multi-link devicereceives the indication element in a broadcasting frame (e.g., a beaconframe) from the AP multi-link device. At block 1204, at the non-APmulti-link device, whether the AP multi-link device has buffered datafor the non-AP multi-link device based on the first indication elementis determined. In some embodiments, the non-AP multi-link devicetransmits a station operation status indication to the AP multi-linkdevice. The station operation status indication may contain informationregarding which station affiliated with the non-AP multi-link device isto be in an awake state. In some embodiments, the non-AP multi-linkdevice receives the buffered data from the AP multi-link device througha communications link that corresponds to the TID when a stationassociated with the TID is to be in the awake state. The non-APmulti-link device may set a station of the non-AP multi-link deviceoperating on the communication link associated with the TID to the awakestate when transmitting the station operation status indication from thenon-AP multi-link device to the AP multi-link device. In someembodiments, the non-AP multi-link device receives a traffic indicationmap (TIM) component of the non-AP multi-link device. In someembodiments, the indication element comprises a bitmap. In someembodiments, the non-AP multi-link device receives the buffered datafrom the AP multi-link device through a communications link that doesnot correspond to the TID when no station operating on the communicationlink associated with the TID is to be in an awake state. In someembodiments, the AP multi-link device and the non-AP multi-link devicesare compatible with an IEEE 802.11 protocol. The AP multi-link devicemay be similar to, the same as, or a component of the AP MLD 102depicted in FIG. 1 . The non-AP multi-link device may be similar to, thesame as, or a component of the non-AP MLDs 104-1, 104-2, 104-3 depictedin FIG. 1 .

In some embodiments, two groups of communications links (e.g., primaryand secondary communications links) are defined for each TID. A firstgroup of links may include one or more links within supported links ofan AP multi-link device (e.g., the AP MLD 102). The TIM bit of the oneor more links may be set to 1 if the AP MLD has a buffered data unit forthe TID. A second group of links may include one or more links withinthe AP MLD's supported links. The TIM bit of the one or more links maynot be set to 1 if the AP MLD has a buffered data unit for the TID. Ifthe AP MLD has a buffered data unit of a TID for a non-AP multi-linkdevice (e.g., the non-AP MLD 104), the AP MLD may set the TIM bit of thefirst group of links for the non-AP MLD to 1. The TIM bit of the secondgroup of links for the non-AP MLD may be set to 0. Each STA of the firstgroup of links affiliated with the non-AP MLD may be set to awake state.Each STA of the second group of links affiliated with the non-AP MLD maybe set to doze state. During the data exchange on the first group oflinks, the non-AP MLD may indicate that STA corresponding to the secondgroup of links may transit to awake state and the data exchange can beextend to the second group of links. In some embodiment, the AP MLD 102and the non-AP MLD 104 may negotiate if the TIM bit of the second groupof links for a TID will be set to 1 or 0 when the AP MLD has a buffereddata unit for the TID. The non-AP MLD may indicate itscapability/preference on setting the TIM bit of the second group oflinks for a TID when the AP MLD has a buffered data unit for the TID.This indication can be done during multi-link association.(Re)-Association Request frame may be used to deliver this information.For a TID, the partitioning between the first group of links and thesecond group of links may be done in static way or in dynamic way. Instatic way, the non-AP MLD associates with the AP MLD and/or themulti-link status changes. In a dynamic way, after association, thepartitioning may be updated from time to time depending on the non-APMLD's power save operation. A variant of an A-control field of a framecan indicate the update. In some embodiments, the non-AP MLD mayindicate its capability/preference on setting the TIM bit of the secondgroup of links for a TID when the AP MLD has a buffered data unit forthe TID. For example, the second group of links may be set to 1 when theAP MLD has buffered data for a TID. The second group of links may be setto 0 when the AP MLD has a buffered data unit for a TID. The AP MLD maydecide if the second group of links will be set to 1 when the AP MLD hasbuffered data for a TID. The size of the first group of links may be 1,which implies that there is only one “primary” link for each TID. Thesecond group of links may be sub-divided into two categories. Forexample, one or more links within the AP MLD's supported links that aTIM bit of the one or more links may be set to 0 if the AP MLD hasbuffered data for the TID. One or more links within the AP MLD'ssupported links that TIM bit of the one or more links may be set to 1 ifthe AP MLD has buffered data for the TID.

In some embodiments, if an AP multi-link device (e.g., the AP MLD 102)has buffered data of a TID for a non-AP multi-link device (e.g., thenon-AP MLD 104) and if all STA affiliated with the non-AP MLDcorresponding to the TID are in doze state, the buffered data of the TIDis delivered using other link(s) associated with the non-AP MLD that isin awake state. In an example operation, for the non-AP MLD, TID0 andTID1 are mapped to link A and link B, respectively. The AP MLD hasbuffered data of both TID0 and TID1 for the non-AP MLD, andconsequently, the AP MLD sends TIM information in a beacon frame, wherethe TIM bit of Link A and Link B corresponding to the non-AP MLD is setto 1. The non-AP MLD may send a PS-Poll frame indicating that only STAon the Link A is in active state. The AP MLD can transmit an aggregatedMAC protocol data unit (AMPDU) that aggregates the buffered data unit ofTID0 and TID1 on Link A.

In some embodiments, if all STAs affiliated with a non-AP multi-linkdevice (e.g., the non-AP MLD 104) mapped to a TID are in doze state, anAP multi-link device (e.g., the AP MLD 102) sends an A-MPDU includingone or more MPDUs with the TID on a link. In an embodiment, the TID ofthe one or more MPDUs are not mapped to the link. In an embodiment, theTID of the one or more MPDUs corresponds to an access category (AC) thatis not higher priority with respect to a primary AC on the link. In someembodiments, if all STAs affiliated with the non-AP MLD mapped to a TIDare in doze state, the AP MLD sends an A-MPDU including only one or moreMPDUs of the TID on a link that the TID is not mapped. If an AP MLD hasa buffered data unit of a TID for a non-AP MLD and if the non-AP MLDreports that all STA affiliated with the non-AP MLD corresponding to theTID are in doze state, the buffered data unit of the TID may bedelivered using other link(s) associated with the non-AP MLD that is inawake state.

In some embodiments, if an AP multi-link device (e.g., the AP MLD 102)indicates in a frame that the AP MLD has a buffered data of a TID for anon-AP multi-link device (e.g., the non-AP MLD 104) and if the AP MLDdoes not receive an indication from the non-AP MLD that at least one ofSTAs affiliated with the non-AP MLD corresponding to the TID is inactive state until a predetermined time, the buffered data of the TID isdelivered using other link(s) associated with the non-AP MLD that is inawake state. The predetermined time may be from the end of transmissionof the frame. In some embodiments, the predetermined time is negotiatedwhen the non-AP MLD associated with the AP MLD or the multi-linkconfiguration is changed.

In some embodiments, an AP multi-link device (e.g., the AP MLD 102)indicates the TID related buffer status information. When the AP MLDsends TIM information (e.g., a TIM bitmap) in a frame (e.g., a beaconframe) on a first communications link, a bit within the TIM informationcorresponding to a non-AP multi-link device (e.g., the non-AP MLD 104)of a link is set to 1 if the AP MLD has buffered data of any TID for thenon-AP MLD. The non-AP MLD may send a second frame (e.g., a PS-Pollframe or a QoS Null frame) to the AP MLD through a communications linkindicating that the non-AP MLD is in active state on the communicationslink. The AP MLD may transmit a third frame to the non-AP MLD on thecommunications link, where the third frame includes information on whichTID(s) the AP MLD has buffered data. In an example operation, the AP MLDhas 3 links—[A, B, C]. For the non-AP MLD, TID0/1/2/3 are mapped to[A,B,C]/[A]/[B]/[C]. Assuming that the AP MLD has buffered data units ofTID0 and TID2 to the non-AP MLD, the AP sends a beacon frame indicatingthat the TIM bit for the non-AP MLD is set to 1, the non-AP MLD sends aPS-Poll frame on link A, and the AP MLD sends back an acknowledgementframe to the non-AP MLD in response to receiving the PS-Poll frame. TheAP MLD may send an A-MPDU including MPDUs with TID 0 on link A. TheA-MPDU may further include information regarding a current buffered dataunit with TID0 and TID2. The non-AP MLD may indicate that the STAsaffiliated with the non-AP MLD on link A and C go to doze state. Furtherdata exchange may happen using link B only. In some embodiments, a QoSControl field of an A-MPDU subframe may include TID information of otherframes than the frame body. For example, bits 8-15 of at least oneapplicable frame (sub)types may be mapped to TID bitmap that either APMLD or non-AP MLD has buffered data. In some embodiments, a variant ofan A-control field of an A-MPDU subframe may include TID information ofother frames than the frame body. In some embodiments, information onwhich TID(s) the AP MLD has a buffered data unit is delivered in adata/control/management/Action frame. In some embodiments, in the thirdframe from the AP MLD, the information on which TID(s) the AP MLD has abuffered data unit is a bitmap, where each bit of the bitmap indicates acorresponding link of the AP MLD that the AP MLD can deliver thebuffered data. The link bitmap may be used for the information on TIDmapping instead.

FIG. 13 is a process flow diagram of a method of multi-linkcommunications in accordance to an embodiment of the invention.According to the method, at block 1302, at an AP multi-link device, afirst group of communications links are mapped to a first trafficidentifier (TID) and a second group of communications links are mappedto a second TID for transmission of data to a non-AP multi-link device,where the first group of communications links and the second group ofcommunications links are subset of communications links that areaffiliated with the AP multi-link device. At block 1304, at the APmulti-link device, an indication element to indicate that the APmulti-link device has buffered data for the first TID and the second TIDis generated. At block 1306, at the AP multi-link device, an indicationfrom the non-AP multi-link device that the non-AP multi-link device isin sleep state for all of the first group of communications links, andthat the non-AP multi-link device is in active state on a thirdcommunications link is received, where the third communications link iswithin the second group of communications links. At block 1308, from theAP multi-link device, the buffered data is transmitted to the non-APmulti-link device through the third communications link. In someembodiments, the buffered data is not transmitted through the firstgroup of communications links. In some embodiments, the AP multi-linkdevice and the non-AP multi-link device are compatible with an IEEE802.11 protocol. The AP multi-link device may be similar to, the sameas, or a component of the AP MLD 102 depicted in FIG. 1 . The non-APmulti-link device may be similar to, the same as, or a component of thenon-AP MLDs 104-1, 104-2, 104-3 depicted in FIG. 1 .

Although the operations of the method(s) herein are shown and describedin a particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operations may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be implemented in anintermittent and/or alternating manner.

It should also be noted that at least some of the operations for themethods described herein may be implemented using software instructionsstored on a computer useable storage medium for execution by a computer.As an example, an embodiment of a computer program product includes acomputer useable storage medium to store a computer readable program.

The computer-useable or computer-readable storage medium can be anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system (or apparatus or device). Examples ofnon-transitory computer-useable and computer-readable storage mediainclude a semiconductor or solid-state memory, magnetic tape, aremovable computer diskette, a random-access memory (RAM), a read-onlymemory (ROM), a rigid magnetic disk, and an optical disk. Currentexamples of optical disks include a compact disk with read only memory(CD-ROM), a compact disk with read/write (CD-R/W), and a digital videodisk (DVD).

Alternatively, embodiments of the invention may be implemented entirelyin hardware or in an implementation containing both hardware andsoftware elements. In embodiments which use software, the software mayinclude but is not limited to firmware, resident software, microcode,etc.

Although specific embodiments of the invention have been described andillustrated, the invention is not to be limited to the specific forms orarrangements of parts so described and illustrated. The scope of theinvention is to be defined by the claims appended hereto and theirequivalents.

1-25. (canceled)
 26. A method of multi-link communications, the methodcomprising: at an access point (AP) multi-link device, allocating aplurality of Association IDs (AIDs) to a plurality of non-AP multi-linkdevices, wherein each non-AP multi-link device is assigned acorresponding AID of the plurality of the AIDs; and at the AP multi-linkdevice, generating a first indication element to indicate a buffereddata configuration at the AP multi-link device for the non-AP multi-linkdevices, wherein each AID is associated with a respective component ofthe first indication element, the respective component set to a firstvalue to indicate buffered data for an associated AID and set to asecond value to indicate no buffered data for the associated AID, thecomponents ordered in the first indication element by AID from lowestAID to highest AID.
 27. The method of claim 26, further comprising: atthe AP multi-link device, generating a second indication element toindicate communications link information associated with the buffereddata configuration at the AP multi-link device, wherein the secondindication element is a link mapping bitmap (LMB), each bit in the LMBindicates whether or not a respective communication link is to deliverthe buffered data of the associated AID, and if the LMB indicates thatno communication link is to deliver the buffered data, then one of apredetermined link and a multi-AP joint transmission is used to deliverthe buffered data.
 28. The method of claim 27, wherein at the APmulti-link device, generating the second indication element to indicatethe communications link information associated with the buffered dataconfiguration at the AP multi-link device comprises: at the APmulti-link device, generating a link mapping bitmap (LMB) for each ofthe AIDs whose corresponding non-AP multi-link device the AP multi-linkdevice has a buffered data unit to be delivered to, wherein the LMBindicates a set of designated communications links through which thebuffered data unit is to be delivered.
 29. The method of claim 28,wherein the buffered data unit is an individually addressed buffereddata unit.
 30. The method of claim 27, further comprising from the APmulti-link device, transmitting the first indication element and thesecond indication element to the non-AP multi-link devices in abroadcast frame.
 31. The method of claim 30, wherein the broadcast framecomprises a beacon frame.
 32. The method of claim 27, wherein at the APmulti-link device, generating the second indication element to indicatethe communications link information associated with the buffered dataconfiguration at the AP multi-link device comprises: at the APmulti-link device, generating a link mapping bitmap (LMB) only for eachof the AIDs whose corresponding non-AP multi-link device the APmulti-link device has an individually addressed buffered data unit to bedelivered to, wherein the LMB indicates a designated set ofcommunications links through which the individually addressed buffereddata unit is to be delivered.
 33. The method of claim 26, wherein at theAP multi-link device, generating the first indication element for theAIDs to indicate the buffered data configuration at the AP multi-linkdevice for the non-AP multi-link devices comprises: at the AP multi-linkdevice, for each AID of the AIDS, setting a corresponding trafficindication map (TIM) component to a specific value when the APmulti-link device has buffered data to be delivered to a correspondingnon-AP multi-link device to which the AID is allocated.
 34. The methodof claim 33, wherein the corresponding TIM component comprises a TIMbit, and wherein the specific value is
 1. 35. The method of claim 26,wherein the buffered data configuration at the AP multi-link devicecomprises information regarding an individually addressed buffered dataunit and a group addressed buffered data unit at the AP multi-linkdevice, and wherein at the AP multi-link device, generating the firstindication element for the AIDs to indicate the buffered dataconfiguration at the AP multi-link device for the non-AP multi-linkdevices comprises: at the AP multi-link device, generating a trafficindication map (TIM) that includes a first section containinginformation regarding the individually addressed buffered data unit anda second section containing information regarding the group addressedbuffered data, wherein the first and second sections havenon-overlapping AID ranges within the AIDs.
 36. The method of claim 26,wherein the AP multi-link device and the non-AP multi-link devices arecompatible with an Institute of Electrical and Electronics Engineers(IEEE) 802.11 protocol.
 37. A multi-link communications systemcomprising: an access point (AP) multi-link device configured to:allocate a plurality of Association IDs (AIDs) to a plurality of non-APmulti-link devices, wherein each non-AP multi-link device is assigned acorresponding AID of the plurality of the AIDs; and generate anindication element to indicate a buffered data configuration at the APmulti-link device for the non-AP multi-link devices, wherein each AID isassociated with a respective component of the indication element, therespective component set to a first value to indicate buffered data foran associated AID and set to a second value to indicate no buffered datafor the associated AID, the components ordered in the indication elementby AID from lowest AID to highest AID.
 38. The multi-link communicationssystem of claim 37, wherein the AP multi-link device and the non-APmulti-link devices are compatible with an Institute of Electrical andElectronics Engineers (IEEE) 802.11 protocol.
 39. A method of multi-linkcommunications, the method comprising: at an access point (AP)multi-link device, mapping a plurality of communications links that areaffiliated with the AP multi-link device to a plurality of trafficidentifiers (TIDs) for a non-AP multi-link device; at the AP multi-linkdevice, generating a component of an indication element to indicate thatthe AP multi-link device has buffered data for a first TID of the TIDsfor the non-AP multi-link device, wherein the component of theindication element is set to a first value to indicate that the APmulti-link device has buffered data for the first TID and set to asecond value to indicate that the AP multi-link device has no buffereddata for the first TID; and transmitting the indication element from theAP multi-link device to the non-AP multi-link device based on the mappedcommunication link to the first TID, wherein Association IDs (AIDs) areallocated to the non-AP multi-link devices, the indication elementcomprising a respective component for each AID, the components orderedin the indication element by AID from lowest AID to highest AID.
 40. Themethod of claim 39, wherein transmitting the indication element from theAP multi-link device to the non-AP multi-link device associated with thefirst TID comprises: broadcasting the indication element from the APmulti-link device in a broadcasting frame.
 41. The method of claim 40,wherein the broadcast frame comprises a beacon frame.
 42. The method ofclaim 39, further comprising: receiving, by the AP multi-link device, astation operation status indication from the non-AP multi-link device,wherein the station operation status indication contains informationregarding which station affiliated with the non-AP multi-link device isto be in an awake state.
 43. The method of claim 42, further comprising:transmitting the buffered data from the AP multi-link device to thenon-AP multi-link device through one of the communications links thatcorresponds to the first TID when a station of the non-AP multi-linkdevice operating on the one of the communications links associated withthe first TID is to be in the awake state.
 44. The method of claim 42,further comprising: at the AP multi-link device, setting a correspondingtraffic indication map (TIM) component of the non-AP multi-link deviceto a specific value.
 45. The method of claim 44, wherein thecorresponding TIM component comprises a TIM bit, and wherein thespecific value is
 1. 46. The method of claim 39, wherein the indicationelement comprises a bitmap.
 47. The method of claim 39, furthercomprising: transmitting the buffered data from the AP multi-link deviceto the non-AP multi-link device through one of the communications linksthat does not correspond to the first TID when no station of the non-APmulti-link device operating on any of the communications linksassociated with the first TID is to be in an awake state.
 48. A methodof multi-link communications, the method comprising: at an access point(AP) multi-link device, mapping a first group of communications links toa first traffic identifier (TID) and a second group of communicationslinks to a second TID for transmission of data to a non-AP multi-linkdevice, wherein the first group of communications links and the secondgroup of communications links are subset of communications links thatare affiliated with the AP multi-link device; at the AP multi-linkdevice, generating an indication element to indicate that the APmulti-link device has buffered data for the first TID and the secondTID, wherein a component of the indication element is set to a firstvalue to indicate that the AP multi-link device has buffered data forthe respective TID and set to a second value to indicate that the APmulti-link device has no buffered data for the respective TID; at the APmulti-link device, receiving an indication from the non-AP multi-linkdevice that the non-AP multi-link device is in sleep state for all ofthe first group of communications links, and that the non-AP multi-linkdevice is in active state on a third communications link, wherein thethird communications link is within the second group of communicationslinks; and from the AP multi-link device, transmitting the buffered datato the non-AP multi-link device through the third communications link,wherein Association IDs (AIDs) are allocated to the non-AP multi-linkdevices, the indication element comprising a respective component foreach AID, the components ordered in the indication element by AID fromlowest AID to highest AID.
 49. The method of claim 48, wherein thebuffered data is not transmitted through the first group ofcommunications links.
 50. The method of claim 48, wherein the APmulti-link device and the non-AP multi-link device are compatible withan Institute of Electrical and Electronics Engineers (IEEE) 802.11protocol.